The overall goal of this project is to develop a novel method for MRI quantification of postinfarct myocardial viability. Ultimately, the commercial embodiment of this method will be a software package that will convert a set of 2D cardiac MRI images to a 3D Myocardial Viability Map (MV) with a voxel-by-voxel resolution. In human clinical use, the package would be interfaced with commercial MRI scanners providing physicians with an immediately available diagnostic tool at the end of the scanning session. The main target market for this package will be the major manufacturers of MRI scanners. Assessment of viability is crucial in the monitoring of myocardial infarction (Ml). A high spatial-resolution method that can distinguish quantitatively between areas of infarct and viable islets in the infarct areas would be useful for clinical decision making. The objective of Phase I is the validation, in a canine model of reperfused Ml, of our method to provide a reliable MV based on MRI. This objective will be achieved via the Specific Aims: 1) Validate in the canine model of reperfused Ml (in 10 dogs) that MV can yield quantitative information on the distribution of viable areas. "Native" images, i.e. images without the application of contrast agent (CA), will be used to test the reliability of maps obtained unaided by contrast enhancement. 2) Compare the MV with the current MRI standard, Delayed Enhancement, in the same dog and MRI session, to ensure comparison at the same time point. 3) Same as Aim 1, except that a single slice MV will be generated after bolus administration of 0.2 mmol/kg of the CA, Magnevist. 4) Same as Aim 1, except MV will be obtained during continuous CA infusion, maintaining a steady state agent concentration in the tissue to allow mapping of the entire left ventricle. 5) Compare the MV with the pathology gold standard, TTC-stained histology. TTC perfusion of the same dogs as above will be carried out at the end of the MRI session and heart will be immediately excised for histology, to ensure comparison with the in vivo results at the same time point. [unreadable] [unreadable] [unreadable]